The worst drought in more than 50 years has been hammering much of the continental U.S. since at least last spring, and NOAA’s Climate Prediction Center says
that while some areas will see some relief in the next few months, most areas will likely remain under persistent drought well into the winter. That doesn’t mean the chances of emerging from this epic dry spell are zero — but in many places, they’re pretty close to it.
In Salisbury, for example, it would take 16.26 inches of precipitation to end the drought by January 1. According to the National Climatic Data Center (NCDC), the probability of this occurring is 2.74 percent. In other words, it’s 97.26 percent certain that it won’t happen.
NCDC updates these scenarios
monthly, calculating the statistical probability that the drought will end over the course of the next of 1,2,3, and 6 months. The complex calculations take into account the Palmer Hydrological Drought Index, as well as local climatological conditions in a given region. Details of these calculations are explained in depth in a paper by Tom Karl et al. 1987.
The map below shows how likely it is that a given region will emerge from drought by the end of the year. The darker the color on the map, the less likely it is that this will happen.
According to a special report from the U.N. Intergovernmental Panel on Climate Change, in the coming decades, droughts in general are likely to be more intense, come more often, and last longer as the world continues to warm.
 Click here for a high-resolution version
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